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Friday, 20 January 2006

Whereas I might say a jumper is blue or red, female acquaintances of mine refer to all sorts of gradations in between, such as navy blue, shocking pink, and many others that I can’t even recall. But does the richness of their colour vocabulary mean they can actually see more colours than me? This is the issue at the heart of the Sapir-Whorf hypothesis – the idea that our perception of the world is anchored in the language that we use. Now Aubrey Gilbert and colleagues have tested the suggestion that if language does affect perception, then it ought to do so more on the right side of space than on the left, because it is the language-dominant left-hemisphere with which we process the right side of space.

In an initial experiment, 13 participants had to distinguish between four similar shades of colour. In terms of wavelength, the shades differed from each other in equally-sized, incremental steps, but two of the shades were what we’d call ‘green’, whereas the other two shades were ‘blue’. Consistent with the Sapir-Whorf hypothesis, participants were quicker at distinguishing between a ‘green’ and a ‘blue’ than between two ‘greens’ or two ‘blues’, but crucially, this advantage only pertained when the colours appeared on the right-hand side of space.

A second experiment showed that this right-hand side advantage for discriminating between shades on either side of the blue/green boundary disappeared when participants were distracted by a simultaneous verbal task, but not when they were distracted by a concurrent spatial task. “The left hemisphere appears to sharpen visual distinctions between lexically defined categories and to blur visual distinctions within these categories, whereas the right hemisphere does so much less”, the researchers said.

If these results can be generalised to the real world, the researchers said “…our representation of the visual world may be, at one and the same time, filtered and not filtered through the categories of language” depending on whether we’re looking to the left or to the right.
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Gilbert, A.L., Regier, T., Kay, P. & Ivry, R.B. (2006). Whorf hypothesis is supported in the right visual field but not the left. Proceedings of the National Academy of Sciences, USA, 103, 489-494.